Battery protection package and process of making the same

ABSTRACT

The present invention discloses small-size battery protection packages and provides a process of fabricating small-size battery protection packages. A battery protection package includes a first common-drain metal oxide semiconductor field effect transistor (MOSFET), a second common-drain MOSFET, a power control integrated circuit (IC), a plurality of solder balls, a plurality of conductive bumps, and a packaging layer. The power control IC is vertically stacked on top of the first and second common-drain MOSFETs. At least a majority portion of the power control IC and at least majority portions of the plurality of solder balls are embedded into the packaging layer. The process of fabricating battery protection packages includes steps of fabricating power control ICs; fabricating common-drain MOSFET wafer; integrating the power control ICs with the common-drain MOSFET wafer and connecting pinouts; forming a packaging layer; applying grinding processes; forming a metal layer; and singulating battery protection packages.

INCORPORATION BY REFERENCE

U.S. Patent Application Publication 2014/0242756 to Xue et al. and U.S.Patent Application Publication 2014/0315350 to Xue et al. are herebyincorporated by reference.

FIELD OF THE INVENTION

This invention relates generally to stacked-die package for batterypower management. More particularly, the present invention relates tosmaller and thinner battery protection packages and a process offabricating the packages.

BACKGROUND OF THE INVENTION

A battery pack of a mobile electronic device may include a batteryprotection circuit module (PCM), cells, and a terminal line. The batteryprotection circuit module of a battery protection package controls thecharge and discharge of the cells. The battery protection package offersover-voltage and over-current protection. Conventional technologies tofurther reduce the size of battery protection integrated circuit (IC)are challenged by several technical difficulties and limitations.Conventional battery protection IC typically includes a power control ICand interconnected dual common-drain metal oxide semiconductor fieldeffect transistors (MOSFETs), which are co-packed in a lead framepackage with a small foot print of a size as small as 2 mm×4 mm.Furthermore, wire bonding is conventionally used for the interconnectionin a semiconductor device package. However, such interconnection moderesults in a high loop of the bonding wire of the clip. Thus, therequirements of obtaining a thinner device cannot be met. In oneexample, the size of a conventional battery protection package is 2 mm×4mm×0.65 mm.

SUMMARY OF THE INVENTION

The present invention discloses small-size battery protection packagesand provides a process of fabricating the battery protection packages.In examples of the present disclosure, a battery protection packageincludes a first common-drain metal oxide semiconductor field effecttransistor (MOSFET), a second common-drain MOSFET, a power controlintegrated circuit (IC), a plurality of solder balls, a plurality ofconductive bumps, and a packaging layer. The power control IC isvertically stacked on top of the first and second common-drain MOSFETs.At least a majority portion of the power control IC and at leastmajority portions of the plurality of solder balls are embedded into thepackaging layer. In examples of the present disclosure, the process offabricating battery protection packages includes steps of fabricatingpower control ICs; fabricating common-drain MOSFET wafer; integratingthe power control ICs with the common-drain MOSFET wafer and connectingpinouts; forming a packaging layer; applying grinding processes; forminga metal layer; and singulating battery protection packages.

The thickness of a battery protection package is reduced by replacingbonding wires with stacking a thin power control IC on thin MOSFETs. Thedrain-source on resistance is reduced and the power consumption isreduced with reduced silicon substrates, with reduced power control ICdie sizes, and with increased MOSFET die sizes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a top view and FIG. 1B is a cross-sectional view of a batteryprotection package in examples of the present disclosure.

FIG. 2A is a top view and FIG. 2B is a cross-sectional view of anotherbattery protection package in examples of the present disclosure.

FIG. 3A is a top view and FIG. 3B is a cross-sectional view of stillanother battery protection package in examples of the presentdisclosure.

FIG. 3C is a top view and FIG. 3D is a cross-sectional view of yetanother battery protection package in examples of the presentdisclosure.

FIG. 4A-FIG. 4F are top views of layout designs of battery protectionpackages in examples of the present disclosure.

FIG. 5A and FIG. 5B are flowcharts of two processes to fabricate twodifferent battery protection packages in examples of the presentdisclosure.

FIG. 6 is a flowchart of a process to fabricate power control integratedcircuits (ICs) in examples of the present disclosure.

FIG. 7 is a flowchart of a process to fabricate common-drain MOSFETsfrom a common-drain MOSFET wafer in examples of the present disclosure.

FIG. 8A and FIG. 8B are flowcharts of processes to connect the powercontrol ICs with the common-drain MOSFET wafers and to connect pinoutsin examples of the present disclosure.

FIG. 9 is a flowchart of a process to mark, singulate, test, and packbattery protection packages in examples of the present disclosure.

FIG. 10 is a flowchart of a process to package battery protectionpackages in examples of the present disclosure.

FIG. 11A and FIG. 11B are a series of cross-sectional views showingvarious processing steps to fabricate power control ICs in examples ofthe present disclosure.

FIG. 12A-FIG. 12F and FIG. 12E-1 are a series of cross-sectional viewsshowing various processing steps to fabricate battery protectionpackages in examples of the present disclosure.

FIG. 13A and FIG. 13B are a series of cross-sectional views showingvarious processing steps to connect the power control ICs with thecommon-drain MOSFET wafers and to connect pinouts in examples of thepresent disclosure.

FIG. 14A and FIG. 14B are another series of cross-sectional viewsshowing various processing steps to connect the power control ICs withthe common-drain MOSFET wafers and to connect pinouts in examples of thepresent disclosure.

FIG. 15A-FIG. 15D are a series of cross-sectional views showing variousprocessing steps to fabricate battery protection packages in examples ofthe present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

The present invention disclosed a low profile battery protection packagewith reduced thermal resistance, with reduced drain-source onresistance, and with reduced power consumption.

FIG. 1A is a top view of a battery protection package 100 and FIG. 1B isa cross-sectional view of the battery protection package 100 along aline AA′ in an example of the present disclosure. The battery protectionpackage 100 comprises first and second common-drain MOSFETs 112 and 112′having a group of bonding pads (not shown) on its top surface with aplurality of solder balls 132 formed on the plurality of bonding pads, apower control IC 122 having a plurality of conductive bumps 142 formedon its top surface (flipped chip), a packaging layer 152, a thick metallayer 172 deposited on the bottom surface of the dual common-drainMOSFETs 112 and 112′, and a backside molded layer 182 attached to thebottom surface of the thick metal layer 172. The power control IC 122 isflipped and vertically stacked on top of the first and secondcommon-drain MOSFETs 112 and 112′. The plurality of conductive bumps 142of the power control IC are attached to another group of bonding pads onthe first and second common-drain MOSFETs 112 and 112′. The packaginglayer 152 partially encapsulated the power control IC 122 and the solderballs 132 with the bottom surface of the power control IC 122 and thetop surfaces of the solder balls 132 exposed. The power control IC 122is electrically coupled to the first common-drain MOSFET 112 and thesecond common-drain MOSFET via the plurality of conductive bumps 142.

The battery protection package 100 further comprises a passivation layer162 having the openings exposing the bonding pads on top surfaces of thefirst and second common-drain MOSFETs 112 and 112′. The passivationlayers may contain polyimide.

A thick metal layer 172, which generally includes Ti/Ni/Ag with athickness of Ag layer being about 5 to 10 microns, is deposited on thebottom surfaces of the first and second common-drain MOSFETs 112 and112′. The backside molded layer 182, or a LC tape, is formed at thebottom of thick metal layer 172 with the thickness of the backsidemolded layer 182 being about 100 microns. Laser-cutting tapes may beattached to the backside molded layer 182.

In examples of the present disclosure, the packaging layer 152 and thebackside molded layer 182 contain epoxy resin.

FIG. 2A is a top view of a battery protection package 200 and FIG. 2B isa cross-sectional view of the battery protection package 200 along aline BB' in another example of the present disclosure. The batteryprotection package 200 comprises first and second common-drain MOSFETs212 and 212′ having a group of bonding pads (not shown) at the topsurfaces with a plurality of solder balls 232 formed on the plurality ofbonding pads, a power control IC 222 having a plurality of conductivebumps 242 formed on the top surface, a packaging layer 252 encapsulatingthe power control IC 222 and the solder balls 232, a thick metal layer272 deposited on the bottom surface of the dual common-drain MOSFETs 212and 212′, and a backside molded layer 282 attached to the bottom surfaceof the thick metal layer 272. The power control IC 222 is flipped andvertically stacked on top of the first and second common-drain MOSFETs212 and 212′, in which the plurality of conductive bumps 242 of thepower control IC 222 are attached and electrically connected to anothergroup of bonding pads on the first and second common-drain MOSFETs 212and 212′. In examples of the present disclosure, the power control IC222 is completely encapsulated by the packaging layer 252 while the topsurfaces of the solder balls 232 is exposed from the top surface of thepackaging layer 252.

The battery protection package 200 also comprises a passivation layer262 having the openings exposing the bonding pads on top surfaces of thefirst and second common-drain MOSFETs 212 and 212′. The passivationlayers may contain polyimide.

In examples of the present disclosure, a thick metal layer 272, whichgenerally includes Ti/Ni/Ag with a thickness of Ag layer being about 5to 10 microns, is deposited on the bottom surfaces of the first andsecond common-drain MOSFETs 212 and 212′. The backside molded layer 282is formed at the bottom of thick metal layer 272 with the thickness ofthe backside molded layer 282 being about 100 microns. Laser-cuttingtapes may be attached to the backside molded layer 282. The overallthickness of the battery protection packages 100 and 200 is about 0.35mm compared with a thickness of 0.65 mm of a conventional batteryprotection package.

FIG. 3A is a top view of still another battery protection package 300and FIG. 3B is a cross-sectional view of the battery protection package300 along a line CC′ in an example of the present disclosure. The topportion of the packaging layer 353 in FIG. 3A is transparent to show aportion of the die paddle 372 of the battery protection package 300. Thebattery protection package 300 comprises first and second common-drainMOSFETs 312 and 312′. A metal layer 391, which generally includesTi/Ni/Ag with a thickness of Ag layer being about 1 micron, is depositedon the bottom surfaces of the first and second common-drain MOSFETs 312and 312′; first and second common-drain MOSFETs 312 and 312′ withdeposited metal layer 391 is attached to a die paddle 372 of a leadframe 382 via silver epoxy 392. A plurality of bonding pads (not shown)is attached to the top surfaces of the first and second common-drainMOSFETs 312 and 312′. A plurality of solder balls 332 is formed on agroup of bonding pads. The battery protection package 300 furthercomprises a power control IC 322 flipped and vertically stacked on topof the first and second common-drain MOSFETs 312 and 312′. A pluralityof conductive bumps 342 formed on the top surface of the power controlIC 322. A first packaging layer 352 partially encapsulated the powercontrol IC 322 and the solder balls 332 with the back surface of thepower control IC 322 (flipped chip) and the top surfaces of the solderballs 132 exposed from the top surface of the first packaging layer 352.The battery protection package 300 further comprises a passivation layer362 and an RDL layer (not shown), which optionally is formed by a doublemetal deposit, formed on top surface of the first and secondcommon-drain MOSFETs 312 and 312′. The power control IC 322 iselectrically coupled to the first and second common-drain MOSFETs 312and 312′ via the plurality of conductive bumps 342 connecting to anothergroup of bonding pads on the first and second common-drain MOSFETs 312and 312′.

In examples of the present disclosure, the plurality of conductive bumps342 may be made of gold, silver, or copper. The lead frame 382 may bemade of copper.

The first common-drain MOSFET 312 and the second common-drain MOSFET312′ are attached to the top surface of the die paddle 372 of the leadframe 382 via silver epoxy 392. The lead frame 382 is half etched at thebottom surface for mold locking. In examples of the present disclosure,external second packaging layer 353 encapsulates the packaging layer352, the first and second common-drain MOSFETs 312 and 312′ the metallayer 391, the die paddle 372, and the lead frame 382. The bottomsurface 384 of the lead frame 382 is exposed from the bottom surface 354of the second packaging layer 353.

FIG. 3C and FIG. 3D shows a battery protection package 301, similar asthe battery protection package 300 of FIG. 3A and FIG. 3B. For thebattery protection package 301, the power control IC 322 is completelyencapsulated by the first packaging layer 352 while the top surfaces ofthe solder balls 332 is exposed from the top surface of the firstpackaging layer 352.

FIG. 4A-FIG. 4F are top views of different layout designs of batteryprotection packages 401-406 in examples of the present disclosure.Pinouts 421-426 and pinouts 431-436 may be exposed solder balls, forexample solder balls 132, 232 or 332 of FIG. 1A, FIG. 2A, FIG. 3A, andFIG. 3C. The thermal resistance of the battery protection package isreduced when the surface areas and the number of the pinouts 421-426 andthe pinouts 431-436 are increased. The drain-source on resistance,Rds(on), and the power consumption are reduced when the thickness of thesilicon wafers, for example, the thickness of the MOSFETs, and thethickness of the power control IC dies, are reduced. Furthermore,Rds(on) and the power consumption are reduced when the size of the powercontrol IC die are reduced, and top surface areas of the MOSFETs areincreased. As shown in FIGS. 4A, 4C and 4E, the backside of the flippedpower control ICs 441, 443, and 445 of the battery protection packages401, 403, and 405 are exposed, while the power control ICs of thebattery protection packages 402, 404, and 406 are completelyencapsulated inside the packages. Each of the battery protectionpackages 401-406 is of rectangular shape and the pinouts at two oppositeedges at the top surface are symmetric with respect to a reflectionalsymmetry line, for example the symmetry lines 411-416. For example, InFIG. 4A, the pinouts 421 and the pinouts 431 are symmetric with respectto the reflectional symmetry lines 411. In FIG. 4B, the pinouts 422 andthe pinouts 432 are symmetric with respect to the reflectional symmetrylines 412. In FIG. 4C, the pinouts 423 and the pinouts 433 are symmetricwith respect to the reflectional symmetry lines 413. An additionaltest-only pinout 453 is located on the reflectional symmetry line 413.In FIG. 4D, the pinouts 424 and the pinouts 434 are symmetric withrespect to the reflectional symmetry line 414, and an additionaltest-only pinout 454 is located on the reflectional symmetry line 414.In FIG. 4E, the pinouts 425 and the pinouts 435 are symmetric withrespect to the reflectional symmetry line 415. In FIG. 4F, the pinouts426 and the pinouts 436 are symmetric with respect to the reflectionalsymmetry line 416.

FIG. 5A is a flowchart of a process 500 to fabricate the batteryprotection packages 100 and 200 in FIG. 1B and FIG. 2B. Process 500 maybegin in block 502.

In block 502, power control ICs are fabricated from an IC wafer. FIG. 6is a flowchart of a process of block 502 to fabricate power controlintegrated circuits (ICs) from an IC wafer in examples of the presentdisclosure. FIGS. 11A and 11B are cross-sectional diagrams showing onepower control IC is fabricated in an example. The process of block 502may begin in block 602.

In block 602 and FIG. 11A, a power control IC wafer 1122 including aplurality of power control IC dies (not shown) is provided. The powercontrol IC wafer 1122 has a first surface 1124 and a second surface1126. Block 602 may be followed by block 604.

In block 604 and FIG. 11A, conductive bumps 1142 are formed on the firstsurface 1124 of the power control IC wafer 1122. Block 604 may befollowed by block 606.

In block 606 and FIG. 11A, a grinding process is applied at the secondsurface 1126 of the power control IC wafer 1122. FIG. 11B shows athinner power control IC wafer 1128 after the grinding process. Inexamples of the present disclosure, the power control IC wafer 1122 ofFIG. 11A is about 625 microns in thickness. In examples of the presentdisclosure, the thinner power control IC wafer 1128 of FIG. 11B is about100 microns in thickness. Block 606 may be followed by block 608.

In block 608, individual power control ICs are singulated from the powercontrol IC wafer.

Block 502 may be followed by block 504. In block 504, common-drainMOSFETs are fabricated from a common-drain MOSFET wafer. FIG. 7 is aflowchart of a process of block 504 to fabricate common-drain MOSFETsfrom a common-drain MOSFET wafer in examples of the present disclosure.The process of block 504 may begin in block 702. There are two optionsfor the process of block 504.

The process of Option 1 begins in block 702. In block 702, acommon-drain MOSFET wafer including a plurality of the dual common-drainMOSFETs is provided. The common-drain MOSFET wafer has a first metallayer deposited and patterned on a first surface. The patterned firstmetal layer may include a first gate electrode connected to a gateregion of the first MOSFET, a first source electrode connected to asource region of the first MOSFET and second gate electrode connected toa second gate region of the second MOSFET and a second source electrodeconnected to a source region of the second MOSFET. Block 702 may befollowed by block 703.

In block 703, a first passivation layer with openings is formed on thefirst surface of the common-drain MOSFET wafer exposing bonding pads ontop surface of each dual common-drain MOSFETs. At least one opening isprovided for each gate or source electrode of each MOSFET in thecommon-drain MOSFET wafer thus at least one bonding pad is provided foreach gate or source electrode of each MOSFET on the first surface of thecommon-drain MOSFET wafer. A processed common-drain MOSFET wafer isformed.

The process of Option 2 begins in block 702. In block 702, acommon-drain MOSFET wafer including a plurality of the dual common-drainMOSFETs provided. The common-drain MOSFET wafer has a first metal layerdeposited and patterned on a first surface. The patterned first metallayer may include a first gate electrode connected to a gate region ofthe first MOSFET, a first source electrode connected to a source regionof the first MOSFET and second gate electrode connected to a second gateregion of the second MOSFET and a second source electrode connected to asource region of the second MOSFET. Block 702 may be followed by block704.

In block 704, a first passivation layer is formed on the first surfaceof the common-drain MOSFET wafer. Block 704 may be followed by block706.

In block 706, part of the first passivation layer is removed forming theopenings to expose portions of the first metal layer. At least oneopening is provided for each gate or source electrode of each MOSFET inthe common-drain MOSFET wafer. Block 706 may be followed by block 708.

In block 708, a redistribution layer, or a second metal layer, isdeposited over the first passivation layer and inside the openings ofthe first passivation layer on the top surface of the common-drainMOSFET wafer and then patterned to form the bonding pads andinterconnections therebetween. Block 708 may be followed by block 710.

In block 710, a second passivation layer is formed on the redistributionlayer exposing only the bonding pads. At least one bonding pad isprovided for each gate or source electrode of each MOSFET on the firstsurface of the common-drain MOSFET wafer. Additional interconnectingbonding pads not connected to any gate or source electrode of the MOSFETmay be provided by the redistribution layer through the openings of thesecond passivation layer. A processed common-drain MOSFET wafer isformed.

Block 504 may be followed by block 506.

In block 506, the power control ICs are connected with the common-drainMOSFET wafer. Pinouts, or solder balls, are formed on a group of thebonding pads of the common-drain MOSFETs. In FIG. 8A and FIG. 8B, thetwo different processes to connect the power control ICs with thecommon-drain MOSFET wafer and to form the solder balls in block 506 aredivided into sub-steps. FIG. 8A is a flowchart of a first process ofblock 506 to connect the power control ICs with the common-drain MOSFETwafer and to connect pinouts in examples of the present disclosure. Theprocess of block 506 may begin in block 802. For the purpose ofsimplicity, cross-section diagrams of FIG. 13A and FIG. 13B only showone power control IC mounted on a dual common-drain MOSFETs of theprocessed common-drain MOSFET wafer.

In block 802 and FIG. 13A, one power control IC 1322 is flipped andmounted on the dual common-drain MOSFETs 1312 and 1312′. The conductivebumps on the power control IC 1322 is electrically coupled to the gateelectrodes of both MOSFETs 1312 and 1312′ at the openings on thepassivation layer. Block 802 may be followed by block 804.

In block 804 and FIG. 13B, solder balls 1332 are dropped on bonding pads(not shown) at other openings on the passivation layer electricallyconnecting to the sources of the dual common-drain MOSFETs 1312 and1312′ with power control IC 1322 mounted thereon. A reflow process isapplied to the solder balls 1332.

FIG. 8B is a flowchart of a process 556 to connect pinouts and toconnect the power control ICs with the common-drain MOSFET wafer and inexamples of the present disclosure. The process 556 may begin in block852. For the purpose of simplicity, cross-section diagrams of FIG. 14Aand FIG. 14B only show one power control IC mounted on a dualcommon-drain MOSFETs of the processed common-drain MOSFET wafer.

In block 852 and FIG. 14A, solder balls 1432 are dropped on bonding pads(not shown) at the openings on the passivation layer electricallyconnecting to the sources of the dual common-drain MOSFETs 1412 and1412′. A reflow process is applied to the solder balls 1432. Block 852may be followed by block 854. Additional solder balls may be dropped onbonding pads that are electrically isolated from the gate and sourceelectrodes of the dual common-drain MOSFETs 1412 and 1412′.

In block 854 and FIG. 14B, one power control IC 1422 is flipped andmounted on the dual common-drain MOSFETs 1412 and 1412′ with solderballs 1432 formed thereon. The conductive bumps on the power control IC1422 is electrically coupled to the gate electrodes of both MOSFETs 1412and 1412′ at the openings on the passivation layer.

Block 506 may be followed by block 508. For the purpose of simplicity,cross-section diagrams of FIG. 12A-FIG. 12F only show one power controlIC mounted on a dual common-drain MOSFETs of the processed common-drainMOSFET wafer.

In block 508 and FIG. 12A and 12B, a packaging layer 1252 is formedcovering a power control IC 1222 flipped and mounted on the dualcommon-drain MOSFETs 1212 and 1212′. In FIG. 12A, the dual common-drainMOSFETs has a first surface 1214 and a second surface 1216. Apassivation layer 1262 including openings is deposited on the firstsurface 1214 of the common-drain MOSFET wafer with bonding pads formedon the first surface 1214 of the common-drain MOSFET wafer at theopenings (not shown). A plurality of conductive bumps 1242 formed at thetop surface of the power control IC 1222 is attached to a firstplurality of bonding pads that are formed at the first surface 1214. Inone example, the first plurality of bonding pads includes at least twobonding pads that are respectively electrically connected to the gateelectrodes of the common-drain MOSFETs 1212 and 1212′. In anotherexample, the first plurality of bonding pads includes one or morebonding pads electrically connected to one or more other bonding padselectrically isolated from any gate or source electrode of thecommon-drain MOSFETs 1212 and 1212′. A plurality of solder balls 1232are attached to a second plurality of bonding pads (not shown) otherthan the first plurality of bonding pads. In one example, the secondplurality of bonding pads includes at least two bonding padsrespectively electrically connecting to the source electrodes of thecommon-drain MOSFETs 1212 and 1212′. In another example, the secondplurality of bonding pads includes one or more bonding pads electricallyconnected to one or more bonding pads of the first plurality of bondingpads. In yet another example, the second plurality of bonding padsincludes one or more bonding pads electrically isolated from any gate orsource electrode of the common-drain MOSFETs 1212 and 1212′. FIG. 12Bshows the packaging layer 1252 having a first surface 1254. The powercontrol IC 1222 and the plurality of solder balls 1232 are entirelyembedded into the packaging layer 1252. Block 508 may be followed byblock 510.

In block 510 and FIG. 12C, a grinding process is applied at the firstsurface 1254 of the packaging layer 1252. In FIG. 12C, the first surface1254 of the packaging layer 1252 is ground until the top surfaces 1234of the solder balls 1232 are exposed. In one example, a top surface 1224of the power control IC 1222 is also exposed. In another example, thepower control IC is embedded into the packaging layer (not shown). Block510 may be followed by block 512.

In block 512 and FIG. 12D, another grinding process is applied at thesecond surface 1216 of the common-drain MOSFETs 1212 and 1212′. FIG. 12Dshows a thinner common-drain MOSFET wafer including dual common-drainMOSFETs 1218 and 1218′ having a ground surface 1220. Block 512 may befollowed by block 514.

In block 514 and FIG. 12E, a metal layer 1272 is deposited on the groundsurface 1220 of the thinner common-drain MOSFET wafer including dualcommon-drain MOSFETs 1218 and 1218′. In one example, the metal layer1272 includes Ti/Ni/Ag with the thickness of Ag layer being about 5microns. In another example, the metal layer 1272 is from 5 microns to10 microns in thickness.

In block 516 and FIG. 12F, a molded layer 1282 is deposited on thebottom surface of the thick metal layer 1272 to support the devicestructure. The thickness of the molded layer 1282 maybe about 100microns. A processed interconnected wafer is formed. Block 516 may befollowed by process 900 of FIG. 9.

FIG. 9 is a flowchart of a process 900 to laser mark, singulate, test,and pack battery protection packages in examples of the presentdisclosure. Block 514 of FIG. 5 may be followed by process 900.

In block 902, laser marks are added to each battery protection packagesat wafer scale level. Block 902 may be followed by block 904.

In block 904, the wafer is cut to singulate the individual markedbattery protection packages. Block 904 may be followed by block 906.

In block 906, the individual marked battery protection packages aretested. Each of the battery protection packages has a passed status isthen packed thus forming a battery protection packages 100 and 200 ofFIG. 1B or FIG. 2B.

FIG. 5B is a flowchart of a process 501 to fabricate the batteryprotection packages 300 and 301 of FIG. 3B and FIG. 3D. The steps ofblocks 502 to 512 are exactly the same as those in process 500 of FIG.5A. Block 512 may be followed by block 513.

In block 513 and FIG. 12E-1, a metal layer 1273 is deposited on theground surface 1220 of the thinned common-drain MOSFET wafer includingdual common-drain MOSFETs 1218 and 1218′. In examples of the presentdisclosure, a metal layer 1273 is deposited on the ground surface 1220of the thinner common-drain MOSFET wafer. In one example, the metallayer 1273 is about 1 micron in thickness. A processed interconnectedwafer is formed. Block 513 may be followed by block 515.

In block 515, battery protection modules are singulated from theprocessed interconnected wafer. Block 516 may be followed by process1000 of FIG. 10.

FIG. 10 is a flowchart of a process 1000 to package battery protectionmodules in examples of the present disclosure. Block 516 of FIG. 5B maybe followed by process 1000. Process 1000 may begin in block 1002.

In block 1002 and FIG. 15A, each of battery protection modules 1502 ofFIG. 12E-1 after singulated from the wafer is attached to each of theplurality of die paddle 1572 of a lead frame 1582 via a silver epoxylayer 1591 so as to form a plurality assemblies. Block 1002 may befollowed by block 1004.

In block 1004 and FIG. 15B, a second packaging layer 1598 is formed oneach of the assemblies. Block 1004 may be followed by block 1006.

In block 1006 and FIG. 15C, a grinding process is applied at a firstsurface of the packaging layer to expose the solder balls and/or theICs. Block 1006 may be followed by block 1008.

In block 1008 and FIG. 15D, another grinding process is applied at asecond surface of the second packaging layer to expose the bottomsurface of the lead frame.

In block 1010, laser marks are added to each battery protection packageson the lead frame. Block 1010 may be followed by block 1012.

In block 1012, the lead frame is cut to singulate the individual markedbattery protection packages. Block 1012 may be followed by block 1014.

In block 1014, the individual marked battery protection packages aretested. Each of the battery protection packages that has a passed statusis then packed thus forming a battery protection packages 300 and 301 ofFIG. 3B or FIG. 3D.

Those of ordinary skill in the art may recognize that modifications ofthe embodiments disclosed herein are possible. For example, thethickness of the metal layer 1272 of FIG. 12E may vary. For example, thenumber of pinouts in a layout design may vary. Other modifications mayoccur to those of ordinary skill in this art, and all such modificationsare deemed to fall within the purview of the present invention, asdefined by the claims.

1. A battery protection package comprising: a first common-drain metaloxide semiconductor field effect transistor (MOSFET) having a firstplurality of bonding pads and a second plurality of bonding pads; asecond common-drain MOSFET having a first plurality of bonding pads anda second plurality of bonding pads; a passivation layer formed on top ofthe first and second common-drain MOSFETs, the passivation layer havingopenings to expose the first and second pluralities of bonding pads ofthe first common-drain MOSFETs and the first and second pluralities ofbonding pads of the second common-drain MOSFETs; a metal layer depositedon bottom surfaces of the first and second common-drain MOSFETs; a powercontrol integrated circuit (IC) vertically stacked on top of the firstand second common-drain MOSFETs; a plurality of solder balls attached tothe first plurality of bonding pads of the first common-drain MOSFETsand the first plurality of bonding pads of the second common-drainMOSFETs; a plurality of conductive bumps; and a packaging layer; whereinat least a majority portion of the power control IC and at leastmajority portions of the plurality of solder balls are embedded into thepackaging layer and wherein the power control IC is electrically coupledto the second plurality of bonding pads of the first common-drain MOSFETand the second plurality of bonding pads of the second common-drainMOSFET via the plurality of conductive bumps.
 2. The battery protectionpackage of claim 1, wherein the packaging layer is a molded layercontaining epoxy resin.
 3. The battery protection package of claim 1,wherein the power control IC is entirely embedded into the packaginglayer.
 4. The battery protection package of claim 1, wherein the powercontrol IC is a flip-chip type IC.
 5. The battery protection package ofclaim 1, wherein the metal layer is attached to a die paddle of a leadframe via silver epoxy.
 6. The battery protection package of claim 5further comprising an external packaging layer, wherein the externalpackaging layer encapsulates the packaging layer, the first and secondcommon-drain MOSFETs, the metal layer, the die paddle, and a majorityportion of the lead frame.
 7. The battery protection package of claim 6,wherein the external packaging layer is transparent.
 8. The batteryprotection package of claim 1, further comprising: a backside moldedlayer or a laser cutting tape attached to the metal layer.
 9. Thebattery protection package of claim 1, wherein the passivation layercontains polyimide.
 10. The battery protection package of claim 1,wherein a top surface of the battery protection package is of arectangular shape having a reflectional symmetry line; wherein thereflectional symmetry line divides the rectangular shape into a firstregion and a second region; and wherein a layout design, on the topsurface of the battery protection package, comprises a first set ofpinouts located in the first region and a second set of pinouts locatedin the second region and wherein the first set of pinouts and the secondset of pinouts are symmetric with respect to the reflectional symmetryline.
 11. The battery protection package of claim 10, further comprisinga test-only pinout located on the reflectional symmetry line.
 12. Aprocess for fabricating battery protection packages, the processcomprising the steps of: fabricating power control integrated circuits(ICs), the step of fabricating power control ICs comprising thesub-steps of: providing a power control IC wafer having a first surfaceand a second surface opposing the first surface of the power control IC;forming conductive bumps on the first surface of the power control ICwafer; thinning the power control IC wafer by grinding at the secondsurface of the power control IC wafer; and singulating the power controlICs from the power control IC wafer; fabricating common-drain metaloxide semiconductor field effect transistors (MOSFETs), the step offabricating common-drain MOSFETs comprising the sub-steps of: providinga common-drain MOSFET wafer having a first surface and a second surfaceopposing the first surface of the common-drain MOSFET wafer; forming afirst passivation layer on the first surface of the common-drain MOSFETwafer; removing part of the passivation layer so as to expose metallines; and forming a second passivation layer; integrating the powercontrol ICs with the common-drain MOSFET wafer and connecting pinouts soas to form an interconnected wafer; forming a packaging layer on theinterconnected wafer, the packaging layer having a first surface;grinding at the first surface of the packaging layer; grinding at thesecond surface of the common-drain MOSFET wafer; depositing a metallayer on the ground second surface of the common-drain MOSFET wafer soas to form a processed interconnected wafer; and singulating the batteryprotection packages from the processed interconnected wafer.
 13. Theprocess of claim 12, wherein the step of integrating the power controlICs with the common-drain MOSFET wafer and connecting pinouts comprises:flipping and mounting the power control ICs on the common-drain MOSFETwafer; and dropping and reflowing solder balls so as to form theconnected pinouts.
 14. The process of claim 12, wherein the step ofintegrating the power control ICs with the common-drain MOSFET wafer andconnecting pinouts comprises: dropping and reflowing solder balls so asto form the connected pinouts; and flipping and mounting the powercontrol ICs on the common-drain MOSFET wafer.
 15. The process of claim14, wherein the power control ICs and the solder balls are exposed afterthe step of grinding at the first surface of the packaging layer. 16.The process of claim 14, wherein the solder balls are exposed after thestep of grinding at the first surface of the packaging layer.
 17. Theprocess of claim 12, further comprising: after the sub-step of removingpart of the passivation layer, depositing a redistribution layer. 18.The method of claim 12, further comprising: after the step of depositinga metal layer on the ground second surface of the common-drain MOSFETwafer and before the step of singulating the battery protection packagesfrom the processed interconnected wafer, laser-marking on the batteryprotection packages; and after the step of singulating the batteryprotection packages from the processed interconnected wafer, testing ofthe battery protection packages; and packing of battery protectionpackages.
 19. The method of claim 12, further comprising: after the stepof singulating the battery protection package from the processedinterconnected wafer, attaching the battery protection packages to diepaddles of a lead frame so as to form assemblies; forming an externalpackaging layer on each of the assemblies, the external packaging layerhaving a first surface and a second surface opposing the first surface;grinding at the first surface of the external packaging layer on each ofthe assemblies; grinding at the second surface of the external packaginglayer on each of the assemblies so as to form a plurality ofdual-packaged battery protection packages; laser-marking on theplurality of dual-packaged battery protection packages; singulating eachof the plurality of dual-packaged battery protection packages by cuttingthe lead frame; testing of the plurality of dual-packaged batteryprotection packages; and packing of the plurality of dual-packagedbattery protection packages.
 20. The method of claim 12, furthercomprising: after the step of depositing a metal layer on the groundsecond surface of the common-drain MOSFET wafer and before the step ofsingulating the battery protection packages from the processedinterconnected wafer, depositing a backside molded layer on a bottomsurface of the metal layer.